The Met Office says the Yasawa and Mamanuca island groups, and the west of Viti Levu will feel the worst of the cyclone, warning of hurricane force winds of 185 kilometres an hour, with gusts up to 270 kilometres an hour.

Strong wind warnings are in force for the whole country and an alert for destructive seas has also been issued.

Forecaster Amit Singh has told Radio Australia's Pacific Beat program the storm remains a category 4.